1. Field of the Invention
The present invention relates to a semiconductor component and a semiconductor device.
2. Description of the Related Art
A conventional MOS semiconductor component is constituted of source/drain regions formed on a semiconductor substrate mainly consisting of silicon and a gate electrode provided on a channel region between the source/drain regions through a gate dielectric layer. A current flowing through the channel region is controlled by controlling a potential in the channel region based on capacitive coupling between the gate electrode and the channel region through the gate dielectric layer. Further, miniaturization of the component has been advanced in order to improve the performance of the component.
However, it cannot be said that the mobility of electrons or holes that move in a semiconductor is high, thus there is a problem that the desired current drivability cannot be obtained. As a countermeasure, a method of using a semiconductor other than silicon for a channel region to obtain high mobility and thereby realizing high current drivability has been examined.
Further, there has been also examined a method of applying a strain to a semiconductor material and thereby modulating a band structure in a semiconductor to obtain high mobility, thus realizing high current drivability. Furthermore, in a p-type semiconductor component in which a current is mainly carried by holes, there is known a technology in which germanium or a mixed crystal of germanium and silicon is used to form a component on a face (110) or a face having a face orientation crystallographically equivalent to the former face, a channel is formed in a direction [110] or a direction crystallographically equivalent to the former direction, and compressive strain is applied in a channel length direction to obtain high mobility (see, e.g., T. Irisawa, et al., “High Performance Multi-Gate pMOSFETs using Uniaxially-Strained SGOI Channels,” in Tech. Dig. of International Electron Device Meeting 2005 pp. 727-730).
A compressive strain can be applied to a semiconductor on which a component is to be formed by providing a semiconductor layer where a component is to be formed on a semiconductor having a lattice constant smaller than that of the semiconductor based on, e.g., epitaxial growth. As a combination adopted when epitaxially growing a semiconductor having a larger lattice constant on a semiconductor having a smaller lattice constant, there is the following combination, for example. That is, it is possible to take a combination that a mixed crystal having a composition ratio of silicon with respect to germanium represented as (1−y)/Y (y satisfies x<y≦1) is epitaxially grown on a mixed crystal having a composition ratio of germanium with respect to silicon represented as x/(1−x) (x satisfies 0≦x<1). Here, lattice constants of silicon and germanium are 0.543 nm and 0.565 nm, respectively. It is known that a lattice constant of a mixed crystal can be obtained by performing linear interpolation with respect to the lattice constants of silicon and germanium in accordance with a composition ratio of these materials.
When x mentioned above is 0 in particular, i.e., when a substrate is formed of pure silicon, a silicon substrate which is extensively utilized in conventional semiconductor components can be used, and hence there is an advantage that formation can be particularly facilitated.
It is to be noted that pure silicon or pure germanium is not usually called a mixed crystal, but each of such pure materials is considered as a special case in which a composition ratio of germanium or silicon is zero, and the pure silicon or the pure germanium is also included in the mixed crystal in this specification.
Although high mobility can be obtained by using germanium for a channel in a p-type semiconductor component and applying compressive strain in a lengthwise direction of the channel as explained above, a strain application method that can obtain such high mobility is not known in an n-type semiconductor component. Therefore, the n-type semiconductor component has a problem that realizing high current drivability is difficult and configuring a complementary semiconductor component is particularly difficult.
Accordingly, there has been demanded realization of a high-performance complementary semiconductor device which can perform a high-speed operation that enables obtaining high mobility to provide an n-type semiconductor component having high current drivability by applying compressive strain to a channel even in the n-type semiconductor component and enables obtaining high current drivability in both the n-type and p-type semiconductor components by applying compressive strain to the n-type semiconductor component as well as the p-type semiconductor component.